Didn't APDS-rounds used to be the spirit-killer ammunition back in sr3?
They still work fine (F4-6 spirits can be hurt easily with an SMG with APDS), but AV is even better.
And a twinked troll with a nodachi could also stand up against spirits of moderate force.
However, really maxed-out, experienced adepts specializing in unarmed combat are probably the runners with the highest damage output per attack, (probably) barring vehicle-only weaponry such as the lovely Itzcoatl railgun.
The advantage of the adepts is that they ignore the Immunity to Normal Weapons alltogether, as their attacks do magical damage anyway.
Also a great way to hurt regenerating critters.